I'm running Ubuntu 11.04 with three monitors. I had trouble installing the virtualbox-ose package through the repositories (I think it was a kernel header issue), so I downloaded the Debian package from the website and installed it.
When I restarted my computer, my monitor settings were messed up. The image is just mirrored across all three monitors (instead of spanning them) and the screen resolution is 1024*786 instead of 1280*1024. I can change it back from mirroring using the Monitor Preferences tool. I can also change two of the monitors back to 1280*1024, but not the third. I wanted to have a look at the xorg.conf file, but I see that 11.04 no longer uses those.
Any idea what might have happened or how to fix this?